1. Field of the Invention
The invention relates to connector devices for use in conjunction with printed circuit boards and more particularly to connector devices for establishing an electrical connection between two printed circuit boards or the like.
2. Related Art
Printed circuit boards and the like are oftentimes provided with an arrangement that allows another circuit board or the like to be electrically connected thereto. For example, a motherboard can be outfitted to allow a daughterboard to be electrically connected thereto, or a backplane board can be outfitted to allow a plug-in board to be electrically connected thereto. FIG. 1 illustrates one such arrangement for electrically interconnecting one printed circuit board with another printed circuit board.
As seen in FIG. 1, an existing printed circuit board 20 (e.g., a motherboard or backplane board) has a connector element 22 mounted thereon. The connector element 22 includes a biasing member 24 and flexible circuitry 26 disposed on the biasing member 24. As seen in FIGS. 2 and 3, the flexible circuitry 26 is provided with a plurality of generally parallel-spaced electrical conductors 28.
With reference once again to FIG. 1, the biasing member 24 is elongated and generally C-shaped with two arm portions 30 that extend along the longitudinal extent of the biasing member 24. The arm portions 30 are spaced apart to define an opening 32 that extends along the longitudinal extent of the connector element 22. The longitudinally extending opening 32 is adapted to receive a printed circuit board 34 or the like.
As seen in FIG. 3, the printed circuit board-like member 34 that is to be inserted into the opening 32 is provided with a plurality of spaced apart electrical contacts 36 that are adapted to cooperate with the electrical conductors 28 on the flexible circuitry 26.
The biasing member 24 can be fabricated from any resilient, spring-like material, such as beryllium copper. The biasing member 24 is designed such that the arm portions 30 provide a biasing force towards one another when the printed circuit board-like member 34 is inserted into the opening 32 between the arm portions 30. Further details associated with the use of a connector member comprised of a combination of flexible circuitry and a biasing member are described, for example, in U.S. Pat. No. 5,195,897, the disclosure of which is incorporated herein by reference.
The connector element 22 can be secured to a mounting block 38 in any suitable manner for purposes of mounting the connector element 22 on the printed circuit board-like member 20. In addition, the ends of the flexible circuitry 26 distal from the arm portions 30 can be provided with leads 40. The leads 40 can be soldered to solder leads or pads (not shown) on the printed circuit board-like member 20 in order to provide electrical connection between the electrical conductors 28 on the flexible circuitry 26 and the electrical contacts (not shown) on the printed circuit board-like member 20. Alternatively, the leads 40 can be compression mounted to the printed circuit board-like member 20 to electrically mate the electrical conductors 28 on the flexible circuitry 26 to the electrical contacts (not shown) on the printed circuit board-like member 20.
As mentioned above, the opening 32 in the connector element 22 is adapted to receive a printed circuit board-like member 34 (e.g., a daughterboard or plug-in board) which has electrical contacts 36 on opposite sides thereof. When the printed circuit board-like member 34 is inserted into the opening 32 in the connector element 22, the electrical contacts 36 on the printed circuit board-like member 34 electrically mate with the electrical conductors 28 on the connector element 22 to thereby establish, by virtue of the electrical mating of the leads 40 with the electrical contacts on the printed circuit board-like member 20, electrical interconnection between the electrical contacts on the two printed circuit board-like member 20, 34.
Although the connector element 22 illustrated in FIGS. 1-3 is well suited for establishing electrical interconnection between two printed circuit board-like members 20, 34, the connector element 22 is susceptible of certain improvements. For example, in some instances, it may be difficult to achieve sufficient electrical contact between the electrical contacts 36 on the printed circuit board-like member 34 and the electrical conductors 28 on the flexible circuitry 26. To explain more fully and with reference to FIGS. 2 and 3, when the printed circuit board-like member 34 is inserted into the opening 32 in the connector element 22, the electrical contacts A', B', C' are designed to electrically mate with electrical conductors A, B, C, respectively on the flexible circuitry 26. If the electrical contact B' on the printed circuit board-like member 34 is recessed slightly with respect to the electrical contacts A', C' (i.e., is not precisely coplanar with respect to the electrical contacts A', C'), the electrical conductors A, C must be capable of being compressed slightly in order to ensure that the electrical conductor B electrically mates with the electrical contact B'. In one respect, it is difficult for the electrical conductors A, B, C to comply with or electrically mate with the electrical contacts A', B', C' on the printed circuit board-like member 34 because the biasing member, which provides the normal contact force, is made from a continuous shape. Typically, a compressible plastic-like material such as polyimide and acrylic adhesive are located between the flexible circuitry 26 and the biasing member 24, and that compressible plastic-like material does allow for some compressibility of the electrical conductors 28 on the flexible circuitry 26. However, if that compressible plastic-like material is not sufficiently compliant, or if a less compressible material is employed, or if the electrical contacts A', B', C' on the printed circuit board-like member 34 are excessively non-coplanar, it may be difficult to ensure that all of the electrical conductors 28 on the flexible circuitry 26 electrically mate with their respective electrical contacts 36 on the printed circuit board-like member 34. In such a situation, a failure may arise.
A related situation also exists with respect to the leads 40 on the flexible circuitry 26 that are to be electrically mated with the electrical contacts on the printed circuit board-like member 20. That is, if the electrical contacts on the printed circuit board-like member 20 are not substantially coplanar with respect to one another (i.e., some of the electrical contacts are elevationally higher or lower than other electrical contacts), it may be difficult to ensure adequate electrical mating of the electrical conductors 28 on the flexible circuitry 26 and the electrical contacts (not shown) on the printed circuit board-like member 20. When the connector element 22 is soldered or pressed down onto the printed circuit board-like member 20, the leads 40 must substantially conform to or lay on top of (i.e., within approximately 0.004") of the corresponding lands or pads (not shown) on the printed circuit board-like member 20. If that does not occur and too much space results between the leads 40 and the lands or pads on the printed circuit board-like member 20, an effective electrical bridge is not formed. Such a situation can arise when the surface of the printed circuit board-like member 20 is warped or when there are variations in elevational height of the lands or pads on the printed circuit board-like member 20.
In light of the foregoing, it would be advantageous and desirable to produce a connector element that allows individual electrical conductors on the flexible circuitry to move relative to one another to ensure an adequate and reliable electrical interconnection between the two printed circuit board-like members 20.